CORS Preflight Issue

[DragonOsman]

Summary

Hi,

I have a CORS preflight request issue that I need resolved.

My main Node.js server file is here on GitHub, and here's the vercel.json file.

The full error messages I'm getting in the console are:

Access to fetch at 'https://personal-library-server.vercel.app/api/users/login' from origin 'https://personal-library-client.vercel.app' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: It does not have HTTP ok status.

Access to fetch at 'https://personal-library-server.onrender.com/api/users/refreshToken' from origin 'https://personal-library-client.vercel.app' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.

The file server.js includes the CORS configuration code, and I also put the same headers and methods in vercel.json. So, why is it stil saying that there's no "Access-Control-Alllow-Origin" header provided for the resource? What am I still missing? Someone please help me. Thanks.

PS. I opened another issue before to report an error I was getting when trying to deploy my server code to Vercel, error code 128, but I resolved it on my own afterwards by changing the use key in vercel.json to "@vercel/node" instead of "vercel/node". I want to close the discussion thread now, but I can't find it.

Example

No response

Steps to Reproduce

Visit https://personal-library-client.vercel.app and try to register. You should see the CORS preflight errors come up in the console. The preflight error on the JWT refresh token route will come first (or at least it does for me, before I try to login (I already have an account there since I've been testing it since before)).

I already linked to the files I think should be looked at. You may also try taking a look at the Register.tsx and Login.tsx files in the client directory.

[DragonOsman]

Update: I deleted the original GitHub repository and made two new repositories for the app: one here for the server and the other here for the client. And then I also made two new Vercel projects, server and client, after deleting the ones from before that were linked to the older repository.

Here's a link to the newly deployed app, a link to server.js where I have CORS set up, and also one to my vercel.json file.

I still have the same error about preflight requests as before. The error appears in the console when you first navigate to the app and a request is made to the refresh token route on the backend. Could someone please review my configuration and code and tell me what I'm doing wrong or what I'm missing? It's a MERN stack app, and the React code is built using Vite.

[github-actions[bot]]

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